Gas turbine aircraft engines may be configured for air/pneumatic starts with the use of an air flow provided from an air source, such as from an auxiliary power unit, an external air compressor or cross-bleed air from an already running engine. An engine's compressor spools are rotated by the air flow acting directly on the compressor blades to start the engine or the air flow drives a separate motor that starts the engine.
A pneumatic starter air valve can control the air flow supplied to the compressor spools or the separate motor for starting the engine. A solenoid of the pneumatic starter air valve can be actuated with a direct current voltage signal to provide the air flow for turning the engine. However, it is harder to control the pneumatic starter air valve response when the solenoid is actuated with a non-direct current voltage signal.
As such, there is a need for improvement.